Applying a timeout in AWS Lambda with node.js

Sometimes a calling a external service or executing a block can may take too long to resolve or reject, and most of times you don't wait for it.

So using Promise.race we can handle it. Next code shows how.

// timeoutPromise
module.exports = {
    timeoutPromise: function (ms, step, promise) {
        // Create a promise that rejects in <ms> milliseconds
        let timeout = new Promise((resolve, reject) => {
            let id = setTimeout(() => {
                clearTimeout(id);
                reject(`Timed out in step: ${step}`);
            }, ms)
        })

        // Returns a race between our timeout and the passed in promise
        return Promise.race([
            promise,
            timeout
        ])
    }
}

// index.js (the lambda)
const util = require('./timeoutPromise');

exports.handler = async (event, context) => {
    try{
        // Create a promise that rejects in <ms> milliseconds
        const doSomething = function() {
            return  new Promise((resolve, reject) => {
                setTimeout(() => resolve('AsyncFunction excecuted on time'), 2000)
            })
        };

        // Apply a timeout of 3 seconds to doSomething
        let doIt = await util.timeoutPromise(3000, 'doSomething step', doSomething())
        return  { body: JSON.stringify(doIt) }
    } catch (error) {
      // Deal with error
      context.fail(error)
    }
};